The novel begins as our narrator, Clay Jensen, mails a mysterious package to someone named Jenny. We soon learn that the package contains the audiotaped suicide note of Hannah Baker, a girl Clay had a crush on before she killed herself about two weeks ago. This is going to be a doozy, Shmoopers.

In the package, there are a total of seven cassette tapes and thirteen stories. On the first tape, Hannah tells her listeners that she holds each of them responsible in some way for her death, and that the tapes will explain why. After listening, each person must give the tapes to the next person on the list. She says that if anybody fails to pass them along, a copy of the recordings will be made public. The tapes also come with a map that listeners are meant to physically follow as they listen to her story.